Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel and dice the sweet potato into 1/2-inch cubes, and chop the red bell pepper into bite-sized pieces.
In a large bowl, toss the broccoli florets, diced sweet potato, and bell peppers with half of the avocado oil, half of the sea salt, and half of the black pepper.
Spread the vegetables in a single layer on the prepared baking sheet and roast for 20-25 minutes until the sweet potatoes are tender and the broccoli edges are crispy.
While the vegetables roast, season the chicken breast on both sides with the remaining sea salt, black pepper, garlic powder, and dried oregano.
Heat the remaining avocado oil in a cast-iron or stainless steel skillet over medium-high heat.
Place the chicken in the hot skillet and sear for 5-7 minutes per side, or until the internal temperature reaches 165°F and the exterior is golden brown.
Remove the chicken from the pan and let it rest for 5 minutes before slicing.
Plate the roasted vegetables alongside the sliced chicken and drizzle everything with fresh lemon juice before serving.